A review of hydrological and chemical stressors in the Adige catchment and its ecological status

Quantifying the effects of multiple stressors on Alpine freshwater ecosystems is challenging, due to the lack of tailored field campaigns for the contemporaneousmeasurement of hydrological, chemical and ecological parameters. Conducting exhaustive field campaigns is costly and hence most of the activities so far have been performed addressing specific environmental issues. An accurate analysis of existing information is therefore useful and necessary, to identify stressors that may act in synergy and to design newfield campaigns.We present an extended review of available studies and datasets concerning the hydrological, chemical and ecological status of the Adige,which is the second longest river and the third largest river basin in Italy. Themost relevant stressors are discussed in the light of the information extracted from a large number of studies. The detailed analysis of these studies identified that hydrological alterations caused by hydropower production are the main source of stress for the freshwater ecosystems in the Adige catchment. However, concurrent effects with other stressors, such as the release of pollutants fromwaste water treatment plants or from agricultural and industrial activities, have not been explored at depth, so far. Awealth of available studies address a single stressor separatelywithout exploring their concurrent effect. It is concluded that a combination of extended experimental field campaigns, focusing on the coupled effects ofmultiple stressors, and modeling activities is highly needed in order to quantify the impact of the multifaceted human pressures on freshwater ecosystems in the Adige river.